#include <stdio.h>

int main(){
    int a = 10;
    int b = 20;
    int c = 0;
    c = a;
    a = b;
    b = c;
    printf("%d %d %d\n", a,b,c);
    change();
}

int change(){
    int a = 10;
    int b = 20;
    int c = a + b;
    a = c - a;
    b = c - b;
    printf("%d %d %d\n", a,b,c);
    add();
    jian();
}

int add(){
    int a = 10;
    printf("%d", a++);
    printf("%d\n",++a);
}

int jian(){
    int b = 10;
    printf("%d",b--);
    printf("%d\n",--b);
}